SQL Server 2012：DATEDIFF 函数以年、日、月表示

Question

我在 SQL Server 2012 中使用 DATEDIFF 函数。我有两个日期，2015-01-01 和 current_date。我需要 DATEDIFF 这两个日期之间的 年、月和日 。以下是我的陈述：

SELECT DATEDIFF(YY, '2015-01-01', GETDATE()) AS 'Years'
SELECT DATEDIFF(MM, '2015-01-01', GETDATE()) AS 'Months'
SELECT DATEDIFF(DD, '2015-01-01', GETDATE()) AS 'Days'

我得到的结果是：年 = 3，月 = 46，天 = 1416

为什么在几个月和几天内增加了一年？

Answer 1

DATEDIFF() 测量两个 date/time 值之间的时间边界数。

因此，对于 year，它测量年份翻转的次数（即新的一年开始）。

对于 month，它测量月份翻转的次数（即新月份开始）。

对于 day，它测量一天翻转的次数（即新的一天开始）。

这些都是相互独立的

我建议您不要尝试获取years/months/days中的值。这是一个难题。 2 月 28 日至 3 月 31 日期间 months/days 的数量是多少？ 1 月 31 日至 2 月 28 日之间？ 1 月 31 日至 3 月 31 日之间？他们不加起来，使这成为一个难题。

Answer 2

也许有点矫枉过正，但如果您对 TVF 持开放态度

例子

Declare @YourTable table (SomeDate date)
Insert Into @YourTable values 
('2015-01-01')

Select A.SomeDate
      ,B.*
 From  @YourTable A
 Cross Apply [dbo].[tvf-Date-Elapsed](SomeDate,GetDate()) B

Returns

SomeDate    Years   Months  Days    Hours   Minutes Seconds
2015-01-01  3       10      16      8       22      40

感兴趣的函数

CREATE FUNCTION [dbo].[tvf-Date-Elapsed] (@D1 DateTime,@D2 DateTime)
Returns Table
Return (
    with cteBN(N)   as (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)),
         cteRN(R)   as (Select Row_Number() Over (Order By (Select NULL))-1 From cteBN a,cteBN b,cteBN c),
         cteYY(N,D) as (Select Max(R),Max(DateAdd(YY,R,@D1))From cteRN R Where DateAdd(YY,R,@D1)<=@D2),
         cteMM(N,D) as (Select Max(R),Max(DateAdd(MM,R,D))  From (Select Top 12 R From cteRN Order By 1) R, cteYY P Where DateAdd(MM,R,D)<=@D2),
         cteDD(N,D) as (Select Max(R),Max(DateAdd(DD,R,D))  From (Select Top 31 R From cteRN Order By 1) R, cteMM P Where DateAdd(DD,R,D)<=@D2),
         cteHH(N,D) as (Select Max(R),Max(DateAdd(HH,R,D))  From (Select Top 24 R From cteRN Order By 1) R, cteDD P Where DateAdd(HH,R,D)<=@D2),
         cteMI(N,D) as (Select Max(R),Max(DateAdd(MI,R,D))  From (Select Top 60 R From cteRN Order By 1) R, cteHH P Where DateAdd(MI,R,D)<=@D2),
         cteSS(N,D) as (Select Max(R),Max(DateAdd(SS,R,D))  From (Select Top 60 R From cteRN Order By 1) R, cteMI P Where DateAdd(SS,R,D)<=@D2)

    Select [Years]   = cteYY.N
          ,[Months]  = cteMM.N
          ,[Days]    = cteDD.N
          ,[Hours]   = cteHH.N
          ,[Minutes] = cteMI.N
          ,[Seconds] = cteSS.N
          --,[Elapsed] = Format(cteYY.N,'0000')+':'+Format(cteMM.N,'00')+':'+Format(cteDD.N,'00')+' '+Format(cteHH.N,'00')+':'+Format(cteMI.N,'00')+':'+Format(cteSS.N,'00')
     From  cteYY,cteMM,cteDD,cteHH,cteMI,cteSS
)
--Max 1000 years
--Select * from [dbo].[tvf-Date-Elapsed] ('1991-09-12 21:00:00.000',GetDate())
--Select * from [dbo].[tvf-Date-Elapsed] ('2017-01-01 20:30:15','2018-02-05 22:58:35')

Answer 3

我对@JohnCappelletti 启发性回答的看法

CREATE FUNCTION [dbo].[tvf_interval_parts] (@start DateTime, @cease DateTime)
Returns Table
RETURN
  SELECT
    *
  FROM
  (
    SELECT
      months / 12   AS years,
      months % 12   AS months
    FROM
    (
      SELECT
        CASE WHEN DATEADD(MONTH, months, @start) > @cease                           THEN months - 1
             WHEN DATEADD(MONTH, months, @start) = DATEADD(MONTH, months, @start-1) THEN months - 1
                                                                                    ELSE months     END   AS months
      FROM
      (
        SELECT DATEDIFF(MONTH, @start, @cease) AS months
      )
        provisional
    )
      adjusted
  )
    interim
  CROSS APPLY
  (
      SELECT
        milliseconds                         / (24 * 60 * 60 * 1000)  AS days,
        milliseconds % (24 * 60 * 60 * 1000) / (     60 * 60 * 1000)  AS hours,
        milliseconds % (     60 * 60 * 1000) / (          60 * 1000)  AS minutes,
        milliseconds % (          60 * 1000) / (               1000)  AS seconds,
        milliseconds % (               1000)                          AS milliseconds
      FROM
      (
        SELECT DATEDIFF_BIG(millisecond, DATEADD(MONTH, 12 * years + months, @start), @cease) AS milliseconds
      )
        provisional
  )
    remainder

此处的用法示例：https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=47b2d437c4cea78d182ce0f63772ef38

SQL Server 2012：DATEDIFF 函数以年、日、月表示

SQL Server 2012 : DATEDIFF function in terms of years, days and months

sql

sql-server

datediff

date-difference